JAVA实现数独游戏：随机生成与难度选择

 import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;
import java.util.*;


public class ShuDu extends JFrame implements ActionListener,ItemListener
{
  private MenuBar menubar=new MenuBar();
  private Menu menu_file=new Menu("文件"); 
  private Menu menu_edit=new Menu("结果");
  private Menu menu_help=new Menu("帮助");
  
  private MenuItem item_ans=new MenuItem("答案");
  private MenuItem item_sol=new MenuItem("提交");
  private MenuItem item_rem=new MenuItem("重来");
  private MenuItem item_next=new MenuItem("开局");
  private MenuItem item_auther=new MenuItem("作者");
  private MenuItem item_exit=new MenuItem("退出");
  private JButton button_sol=new JButton("提交");
  private JButton button_ans=new JButton("答案");
  private JButton button_rem=new JButton("重来");
  private JButton button_ext=new JButton("退出");
  private JButton button_aur=new JButton("作者");
  private JButton button_next=new JButton("开局");
  private JComboBox box=new JComboBox();
  
  static int data[][]=new int[10][10];
  static int ansdata[][]=new int[10][10];

 static int row[][]=new int[10][10];
 static int col[][]=new int[10][10];
 static int sql[][][]=new int[4][4][10];
 static JTextField text[][]=new JTextField[10][10];
 static String atext[][]=new String[10][10];
 static int hard=2;
 static int datahard[]={2,3,5}; // 不同的难度
 
 class ShuDuAns extends JFrame
 {
  private JTextField atext[][]=new JTextField[10][10];
  public ShuDuAns()
   {
    super("答案");
    this.setSize(300,300);
    this.setLocation(200,200);
    this.setVisible(true);
    this.setResizable(false);
    JPanel apanel_but=new JPanel(new FlowLayout(FlowLayout.LEFT));
    JPanel apanel_txt=new JPanel(new GridLayout(3,3,2,2));
    JPanel apanel[]=new JPanel[10];
    
    for(int i=1;i<=9;i++)
    {
     apanel[i]=new JPanel(new GridLayout(3,3));
     apanel_txt.add(apanel[i]);
     int m=(i+2)/3*3-2;
     int n=((i-1)%3+1)*3-2;
     for(int j=m;j<=m+2;j++)
     {